pinctrl: stm32: defer probe if reset resource is not yet ready

Defer probe when pin controller reset is defined in the system resources
but not yet probed.
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
Link: https://lore.kernel.org/r/20200615125407.27632-3-alexandre.torgue@st.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/stm32/pinctrl-stm32.c

@@ -84,6 +84,7 @@ struct stm32_pinctrl_group {
 struct stm32_gpio_bank {
 	void __iomem *base;
 	struct clk *clk;
+	struct reset_control *rstc;
 	spinlock_t lock;
 	struct gpio_chip gpio_chip;
 	struct pinctrl_gpio_range range;
@@ -1202,13 +1203,11 @@ static int stm32_gpiolib_register_bank(struct stm32_pinctrl *pctl,
 	struct of_phandle_args args;
 	struct device *dev = pctl->dev;
 	struct resource res;
-	struct reset_control *rstc;
 	int npins = STM32_GPIO_PINS_PER_BANK;
 	int bank_nr, err;
 
-	rstc = of_reset_control_get_exclusive(np, NULL);
-	if (!IS_ERR(rstc))
-		reset_control_deassert(rstc);
+	if (!IS_ERR(bank->rstc))
+		reset_control_deassert(bank->rstc);
 
 	if (of_address_to_resource(np, 0, &res))
 		return -ENODEV;
@@ -1516,6 +1515,11 @@ int stm32_pctl_probe(struct platform_device *pdev)
 		struct stm32_gpio_bank *bank = &pctl->banks[i];
 
 		if (of_property_read_bool(child, "gpio-controller")) {
+			bank->rstc = of_reset_control_get_exclusive(child,
+								    NULL);
+			if (PTR_ERR(bank->rstc) == -EPROBE_DEFER)
+				return -EPROBE_DEFER;
+
 			bank->clk = of_clk_get_by_name(child, NULL);
 			if (IS_ERR(bank->clk)) {
 				if (PTR_ERR(bank->clk) != -EPROBE_DEFER)